1. Field
The present inventive concept is directed to a planetary roller transmission device which uses a planetary roller mechanism and to a vehicle which comprises the planetary roller transmission device. More specifically, the inventive concept relates to a planetary roller transmission device, which efficiently transmits large torques, and to a vehicle, which comprises the planetary roller transmission device.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication H6-280961 (Patent Document 1) is an example of a conventional transmission device, which uses a conventional planetary roller mechanism. The conventional planetary roller mechanism is illustrated in FIG. 5.
In FIG. 5, an input shaft 207 is rotatably supported, via a bearing 205, by a flange 203 mounted on one end side of a cylindrical housing 201, and an output shaft 213 is rotatably supported, via a bearing 211, by a flange 209 mounted on the other end side of the housing 201. The input shaft 207 and the output shaft 213 are disposed on the same axis, and the inner end portion of the input shaft 207 is rotatably supported by the output shaft 213 via a bearing 215.
A tapered sun roller 217 is integrally attached, via a key 219, to the inner end side of the input shaft 207, and a plurality of planetary rollers 221 are rollably disposed on the outer periphery of the sun roller 217. The planetary rollers 221 are rotatably supported by holders 225, which are rotatably supported by the input shaft 207 via bearings 223. The planetary rollers 221 internally and rollably contact output rings 227 integrally attached via keys to a cup-shaped inner end side of the output shaft 213.
The plurality of planetary rollers 221 are held rollably through pinching pressure between the sun roller 217 and the output rings 227.
A taper portion 221T is formed on one end side of each planetary roller 221, and the taper portions 221T internally and rollably contact shift rings 229. The shift rings 229 are integrally supported by a movable member 233, which is movably screwed to a screw member 231 that is rotatably supported by the housing 201. Accordingly, the shift rings 229 integrally move in the axial direction of the input shaft 207 and the output shaft 213 when the movable member 233 moves due to the rotation of the screw member 231, and, thus, the contact position of the taper portion 221T on the planetary rollers 221, and the shift rings 229 can be varied.
As is described above, in the conventional planetary roller mechanism, the planetary rollers 221 are pinched between the sun roller 217 and the output rings 227. Therefore, when the contact pressure between the sun roller 217 and the planetary rollers 221 is large, the contact pressure between the planetary rollers 221 and the output rings 227 is also increased, but the contact pressure between the shift rings 229 and the planetary rollers 221 cannot be increased.
Accordingly, it is impractical to improve transmission efficiency in the conventional planetary roller mechanism by increasing the contact pressure between the sun roller 217 and the planetary rollers 221, the contact pressure between the output rings 227 and planetary rollers 221, and the contact pressure between the shift rings 229 and the planetary rollers 221. Moreover, it is difficult to increase the contact pressure between the planetary rollers 221 and the shift rings 229 due to the planetary rollers 221 being cantilever and the taper portions 221T easily bending.
Embodiments of the present inventive concept solve the above problems by providing a planetary roller transmission device and a vehicle comprising the planetary roller transmission device in which the contact pressure of the planetary rollers can be increased relative to the sun roller, the output rings and the shift rings, thereby increasing the transmission efficiency.